What was sulfuric acid originally used for?

The historical name of this acid is oil of vitriol.

Sulfuric acid was called "oil of vitriol" by medieval European alchemists because it was prepared by roasting "green vitriol" (iron (II) sulfate) in an iron retort.

In the seventeenth century, the German-Dutch chemist Johann Glauber prepared sulfuric acid by burning sulfur together with saltpeter (potassium nitrate, KNO3), in the presence of steam.

As saltpeter decomposes, it oxidizes the sulfur to SO3, which combines with water to produce sulfuric acid.

In 1736, Joshua Ward, a London pharmacist, used this method to begin the first large-scale production of sulfuric acid.

But in answer to your question – sulfuric acid had a medical use.

Dr. Crawford M. Long was born in 1815 at Danielsville in Georgia, U.S., got his medical degree from the University of Pennsylvania, and practiced as surgeon.

The pain of the patient during surgery upset him and he wanted to find a solution — a dream of a painless surgery.

For years it was known that the ‘sweet oil of vitriol’ (a mixture of ethanol and sulfuric acid) sent chickens to sleep, but no one thought of its clinical use.

The credit for transformation of the ‘sweet oil of vitriol’ to ‘diethyl ether’ as an anaesthetic agent goes to Dr. Long.

On March 30, 1842, at the age of 27, he administered ‘diethyl ether’ to a patient and removed a tumour in the neck, the first-ever painless surgery.

It was like sheer magic that took away the pain and anxiety of surgical procedure. But, unlike the usual magician, he never bothered about the audience. No wait for claps, no expectation of applause.

Despite this stunning achievement, this medical milestone remained only a matter of scientific transaction among his colleagues.

Original I don't know, but for years its been used in Lead Acid batteries (car batteries) and other batteries before then